Dermatology Flashcards
MLA conditions and preperation
Erythema multiforme
Hypersensitivity reaction that is most commonly triggered by infections.
It may be divided into minor and major forms.
Typically appears like target lesions on the skin.
Features of Erythema multiforme
-target lesions
-initially seen on the back of the hands / feet before spreading to the torso
-upper limbs are more commonly affected than the lower limbs
-pruritus is occasionally seen and is usually mild
Causes of erythema multiforme
-viruses: herpes simplex virus (the most common cause), Orf (Parapox virus)
-idiopathic
-bacteria: Mycoplasma, Streptococcus
-drugs: penicillin, sulphonamides, -carbamazepine, allopurinol, NSAIDs, oral -contraceptive pill, nevirapine
-connective tissue disease e.g. Systemic lupus -erythematosus
-sarcoidosis
-malignancy
Erythema multiforme major
The more severe form, erythema multiforme major is associated with mucosal involvement.
Who gets erythema multiforme commonly
most common in young adults (aged 20–40 years) with a modest predominance in males. There is no association with race.
HLA-DQB1*0301 allele associated with herpes
Medications which may trigger erythema multiforme
Antibiotics (including erythromycin, nitrofurantoin, penicillins, sulfonamides, and tetracyclines)
Anti-epileptics
Non-steroidal anti-inflammatory drugs
Vaccinations (most common cause in infants).
Conditions associated with erythema multiforme
Inflammatory bowel disease
Hepatitis C
Leukaemia
Lymphoma
Solid organ cancer malignancy.
Clinical features of ertythema multiforme
fatigue,
malaise,
myalgia,
or fever.
These likely represent the course of precipitating illness rather than true prodrome.
Serious complications of erythema multiforme
Keratitis
Conjunctival scarring
Uveitis
Permanent visual impairment.
What tests should be carried out if erythema multiforme is suspected
Complete blood examination
Liver functions tests
ESR
Serological testing for infectious causes
Chest x-ray.
Skin biopsy with histopathology and direct immunofluorescence
Treatment of erythema multiforme
- self limiting condition
- cease medication which causes
- prednisone for mucosal disease
- antiviral therapy aciclovir
Erythema nodosum
inflammatory disorder affecting subcutaneous fat. It most commonly presents as bilateral tender red nodules on the anterior shins
Who gets erythema nodosum
Erythema nodosum can occur in all ethnicities, sexes, and ages, but is most common in women between the ages of 25 and 40
It is 3–6 times more common in women than in men except before puberty when the incidence is the same in both sexes
Causes of erythema nodosum?
- hypersensitivity reaction of unknown cause in 55%
-usually associated with drugs, infection or malignancy
Throat infections (streptococcal disease or viral infection)
Primary tuberculosis (TB), a rare cause in New Zealand
Yersinia infection; this causes diarrhoea and abdominal pain
Chlamydia infection
Fungal infection: histoplasmosis, coccidioidomycosis
Parasitic infection: amoebiasis, giardiasis
Viral and bacteria diseases which are associated with erythema nodosum
-HSV
- viral hepatitis
-HIV
- campylobacter infection
- Salmonella infection
Drugs which cause erythema nodosum
Sulfonamide
Amoxicillin
Oral contraceptive
Non-steroidal anti-inflammatory drugs
Bromide
Salicylate
Iodide
Gold salt
Inflammatory diseases which cause erythema nodosum
Inflammatory bowel disease (ulcerative colitis or Crohn disease)
Sarcoidosis (11–-25%); X-ray shows bilateral hilar adenopathy in Löfgren syndrome
Malignancy
Lymphoma
Leukaemia
Behçet disease
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Pregnancy
Investigations for erythema nodosum
Complete blood count with differential, C-reactive protein levels (infectious and inflammatory causes)
Chest X-ray (tuberculosis and sarcoidosis)
Throat swab and anti-streptolysin O and streptodornase serology (streptococcal infection)
Viral serology (preferably two samples at four-week intervals)
Stool culture and evaluation for ova and parasites in patients with gastrointestinal symptoms
Mantoux test or QuantiFERON gold (tests for TB).
Deep incisional or excisional skin biopsy.
Septal Panniculitis
Various forms of scleroderma
Medium vessel vasculitis, for example, due to polyarteritis nodosa in which there are tender subcutaneous nodules associated with ulceration, necrosis, livedo racemosa, fever, joint pain, myalgia, and peripheral neuropathy
Necrobiosis lipoidica
Eosinophilic panniculitis
Rheumatoid nodule.
Treatment for erythema nodosum
Pain management may include extended rest, colchicine (1–2 mg/day), NSAIDs (non-steroidal anti-inflammatory drugs), and venous compression therapy [4].
Systemic corticosteroids (1 mg/kg daily until resolution of erythema nodosum) may be prescribed if infection, sepsis, and malignancy have been ruled out [9,11].
Oral potassium iodide as a supersaturated solution (400–900 mg/day) may be prescribed for one month if available
Guttate psoriasis
Distinct variant of psoriasis that is classically triggered by streptococcal infection (pharyngitis or perianal)
More common in Childern and adolescents
Features of guttate psoriasis
Tear drop papules on the trunk and limbs
gutta is Latin for drop
pink, scaly patches or plques of psoriasis
tends to be acute onset over days
Typically triggered by Streptococcal infection
What is the managment of guttate psoriasis
most cases resolve spontaneously within 2-3 months
there is no firm evidence to support the use of antibiotics to eradicate streptococcal infection
topical agents as per psoriasis
UVB phototherapy
tonsillectomy may be necessary with recurrent episodes
Prodome (guttate vs Pityriasis rosea)
Many patients report recent respiratory tract infections but this is not common in questions
Appearance (Guttate vs Pityriasis rosea)
‘Tear drop’, scaly papules on the trunk and limbs
Herald patch followed 1-2 weeks later by multiple erythematous, slightly raised oval lesions with a fine scale confined to the outer aspects of the lesions.
May follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to the line of Langer. This may produce a ‘fir-tree’ appearance
Treatment (Guttate vs Pityriasis rosea)
Most cases resolve spontaneously within 2-3 months
Topical agents as per psoriasis
UVB phototherapy
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Self-limiting, resolves after around 6 weeks
Pityriasis rosea
Pityriasis rosea describes an acute, self-limiting rash which tends to affect young adults
characterised by a large circular or oval “herald patch”, usually found on the chest, abdomen, or back
Herald patch is followed some time later, typically two weeks or so, by the development of smaller scaly oval red patches, resembling a Christmas tree, distributed mainly on the chest and back.
What are the features of pityriasis rosea
In the majority of patients there is no prodrome, but a minority may give a history of a recent viral infection
herald patch (usually on trunk)
followed by erythematous, oval, scaly patches which follow a characteristic distribution with the longitudinal diameters of the oval lesions running parallel to the line of Langer. This may produce a ‘fir-tree’ appearance
Managment of pitiyriasis rosea
self-limiting - usually disappears after 6-12 weeks
Common microbe in animal bites
polymicrobial but the most common isolated organism is Pasteurella multocida.
Managment of animal bites
cleanse wound.
Puncture wounds should not be sutured closed unless cosmesis is at risk
current BNF recommendation is co-amoxiclav
if penicillin-allergic then doxycycline + metronidazole is recommended
Microbes which are found in human bites
Common organisms include:
Streptococci spp.
Staphylococcus aureus
Eikenella
Fusobacterium
Prevotella
Reccomended Tx for human and animal bites
Co-amoxiclav
other investigations/ tx after exposure to animal or human bites
HIV (6 weeks before sero-conversion, cosider pep)
Hepatitis C
Bed bugs
Cimex hemipteru.
Cimex lectulatius
Clinical features of bed bug bites
A small punctum (hole) may be seen at the site of the bite.
Some people develop cutaneous reactions with pruritus (itching) and (most commonly) 2–5 mm red bumps.
Purpura, petechiae, vesicles, urticaria, pustules, localised infection, and (rarely) anaphylaxis may also develop.
Hypersensitivity reactions may develop in some who become sensitised to bed bug saliva.
If bites are seen, they are often reported to be in a linear formation in groups of three, sometimes termed the ‘breakfast, lunch, and dinner’ pattern.
Bed bugs feed on exposed skin, therefore the limbs are a more common site for bites.
complications of bed bug bites
Localised infections including cellulitis, folliculitis, and infected eczema
Anaemia (a few reports of this secondary to chronic bed bug infestation)
Anaphylaxis
Psychological distress.
prophylaxis/ prevent future cases of bed bugs
Bed bug numbers may be controlled by hot-washing bed linen and using mattress covers.
managment of bed bug bites
A cool, damp cloth over areas of irritation can improve symptoms
Itchy lesions can be treated with topical steroids and/or oral antihistamines (hydrocortisone and ceterazie)
Secondary infection should be treated with antibiotics (Cephalexin, Doxycycline
Trimethoprim-sulfamethoxazole (co-trimoxazole)
Clindamycin)
Rare systemic anaphylactic reactions to bed bug bites may require intramuscular adrenaline.
Lyme disease microorganism
Borrelia burgdorferi
Early features of lyme disease in the first 30 days
erythema migrans
‘bulls-eye’ rash is typically at the site of the tick bite
typically develops 1-4 weeks after the initial bite but may present sooner
usually painless, more than 5 cm in diameter and slowlly increases in size
present in around 80% of patients.
Systemic features of lyme disease
headache
lethargy
fever
arthralgia
Later features of lyme disease
cardiovascular
heart block
peri/myocarditis
neurological
facial nerve palsy
radicular pain
meningitis
Investigations of Lyme disease
NICE recommend that Lyme disease can be diagnosed clinically if erythema migrans is present
erythema migrans is therefore an indication to start antibiotics
enzyme-linked immunosorbent assay (ELISA) antibodies to Borrelia burgdorferi are the first-line test
if negative and Lyme disease is still suspected in people tested within 4 weeks from symptom onset, repeat the ELISA 4-6 weeks after the first ELISA test. If still suspected in people who have had symptoms for 12 weeks or more then an immunoblot test should be done
if positive or equivocal then an immunoblot test for Lyme disease should be done
Erythema Migrans
typically a circular red area that sometimes clears in the middle, forming a bull’s-eye pattern.
Managment of tick bites
tick bites can be a relatively common presentation to GP practices, and can cause significant anxiety
if the tick is still present, the best way to remove it is using fine-tipped tweezers, grasping the tick as close to the skin as possible and pulling upwards firmly. The area should be washed following.
NICE guidance does not recommend routine antibiotic treatment to patients who’ve suffered a tick bite
fIrst aid response to
burns
airway, breathing, circulation
burns caused by heat: remove the person from the source. Within 20 minutes of the injury irrigate the burn with cool (not iced) water for between 10 and 30 minutes. Cover the burn using cling film, layered, rather than wrapped around a limb
electrical burns: switch off power supply, remove the person from the source
chemical burns: brush any powder off then irrigate with water. Attempts to neutralise the chemical are not recommended
Wallace Rule
Wallace’s Rule of Nines: head + neck = 9%, each arm = 9%, each anterior part of leg = 9%, each posterior part of leg = 9%, anterior chest = 9%, posterior chest = 9%, anterior abdomen = 9%, posterior abdomen = 9%
the palmar surface is roughly equivalent to 1% of total body surface area (TBSA). Not accurate for burns > 15% TBSA
Lund and Browder chart: the most accurate method
Superficial epidermal
-first degree
-Red and painful, dry, no blisters
Partial thickness (superficial dermal)
- second degree burn
-Pale pink, painful, blistered. Slow capillary refill
Partial thickness (deep dermal)
- second degree burn
Typically white but may have patches of non-blanching erythema. Reduced sensation, painful to deep pressure
Full thickness burn
- third degree burn
-White (‘waxy’)/brown (‘leathery’)/black in colour, no blisters, no pain
when referral to secondary care needed for burns?
-all deep dermal and full-thickness burns.
superficial dermal burns of more than 3% TBSA in adults, or more than 2% TBSA in children
superficial dermal burns involving the face, hands, feet, perineum, genitalia, or any flexure, or circumferential burns of the limbs, torso, or neck
any inhalation injury (even small injury next to the nose)
any electrical or chemical burn injury
suspicion of non-accidental injury
1st managmenet of burn
initial first aid as above
review referral criteria to ensure can be managed in primary care
superficial epidermal: symptomatic relief - analgesia, emollients etc
superficial dermal: cleanse wound, leave blister intact, non-adherent dressing, avoid topical creams, review in 24 hours
Burns which impact the airways
-smoke inhalation can result in airway oedema
-early intubation should be considered e.g. if deep burns to the face or neck, blisters or oedema of the oropharynx, stridor etc
IV fluids - when required in burns
- Intravenous fluids will be required for children with burns greater than 10% of total body surface area.
-Adults with burns greater than 15% of total body surface area will also require IV fluids.
Parkland formula
volume of fluid= total body surface area of the burn % x weight (Kg) x4.
half fluid needs to be given in the first 8 hours
also insert urinary catheter
Managment of complex burns
Complex burns, burns involving the hand perineum and face and burns >10% in adults and >5% in children should be transferred to a burns unit.
Circumferential burns
Circumferential burns affecting a limb or severe torso burns impeding respiration may require escharotomy to divide the burnt tissue.
Escharotomies
Indicated in circumferential full thickness burns to the torso or limbs.
Careful division of the encasing band of burn tissue will potentially improve ventilation (if the burn involves the torso), or relieve compartment syndrome and oedema (where a limb is involved)
Some causes of pruritis
hyper- and hypothyroidism
diabetes
pregnancy
‘senile’ pruritus
urticaria
skin disorders: eczema, scabies, psoriasis, pityriasis rose
Pruritis and liver- other symptoms
History of alcohol excess
Stigmata of chronic liver disease: spider naevi, bruising, palmar erythema, gynaecomastia etc
Evidence of decompensation: ascites, jaundice, encephalopathy
Pruritis and iron deficiency
Pallor
Other signs: koilonychia, atrophic glossitis, post-cricoid webs, angular stomatitis
Prutitis and Polycythemia
Pruritus particularly after warm bath
‘Ruddy complexion’
Gout
Peptic ulcer disease
Chronic kidney disease and pruritis
Lethargy & pallor
Oedema & weight gain
Hypertension
Lymphoma and pruritis
Night sweats
Lymphadenopathy
Splenomegaly, hepatomegaly
Fatigue
Signs of pruritis
excoriations
Persistent scratching over a period of time may lead to:
Lichenification (thickened skin, lichen simplex)
Prurigo papules and nodules.
epidemiology of pruritis
Affects all people
The incidence of chronic pruritus increases with age, it is more common in women, and in those of Asian background.
localised rashes (scalp, back, hands, genitals, legs and feet)
Scalp: seborrhoeic dermatitis, head lice
Back: Grover disease
Hands: pompholyx, irritant and/or allergic contact dermatitis
Genitals: vulvovaginal Candida albicans infection, lichen sclerosus
Legs: venous eczema
Feet: tinea pedis
Neuropathic localised pain (face, hands, arm, back, geniral, dermatomal)
Face: trigeminal trophic syndrome
Hand: cheiralgia paraesthetica
Arm: brachioradial pruritus
Back: notalgia paraesthetica
Genital: pruritus vulvae, pruritus ani
Dermatomal: herpes zoster (shingles) during the recovery phase
Managment of pruritis
Wet dressings or tepid shower to cool the skin
Calamine lotion (contains phenol, which cools the skin): avoid on dry skin and limit use to a few days
Menthol/camphor lotion: gives a chilling sensation
Local anaesthetics, such as pramoxine (also called pramocaine), applied to small itchy spots such as insect bites
Regular use of emollients, especially if skin is dry
Mild topical corticosteroids for short periods
Topical calcineurin inhibitors are also used to reduce itch associated with inflammatory skin conditions
Topical doxepin, a tricyclic antidepressant and antihistamine, is an antipruritic used in eczema.
antidepressants and antipruritic action
Doxepin and amitriptyline are tricyclic antidepressants have antipruritic action and act on the central and peripheral nervous systems.
Tetracyclic antidepressants such as mirtazepine and selective serotonin reuptake inhibitors (paroxetine, sertraline, fluoxetine) may also help some patients with severe itch including when it is caused by cholestasis, T-cell lymphoma, malignancy or a neuropathic cutaneous dysaesthesia.
Anti-epileptic drugs such as sodium valproate, gabapentin and prega
Asprin and pruritis
Aspirin is sometimes effective if pruritus is mediated by kinins or prostaglandins and is noted to be effective in patients with pruritus due to polycythaemia vera. Note: aspirin may cause or aggravate itch in some patients.
Phototherapy
Ultraviolet B (UVB) phototherapy alone, or in conjunction with UVA, has been shown to be helpful for pruritus associated with chronic kidney disease, psoriasis, atopic eczema and cutaneous T-cell lymphoma.
Keloid scars
Pre-disposing factors of Keloid scars
ethnicity: more common in people with dark skin
occur more commonly in young adults, rare in the elderly
common sites (in order of decreasing frequency): sternum, shoulder, neck, face, extensor surface of limbs, trunk
erythema migrans
- Rash associated with Lyme disease
- centre dark, one round outside is clear
Uticaria
Urticaria describes a local or generalised superficial swelling of the skin. The most common cause of urticaria is allergy although non-allergic causes are seen.
-pale, pink raised skin. Variously described as ‘hives’, ‘wheals’, ‘nettle rash’
pruritic
what are the classifcations of uticaria
-Acute urticaria (< 6 weeks duration, and often gone within hours to days)
-Chronic urticaria (> 6 weeks duration, with daily or episodic weals)
acute causes of uticaria
Acute viral infection — upper respiratory infection, viral hepatitis, infectious mononucleosis, mycoplasma
Acute bacterial infection — dental abscess, sinusitis
Food allergy (IgE mediated)—usually milk, egg, peanut, shellfish
Drug allergy (IgE mediated drug-induced urticaria) — often an antibiotic
Drug-induced urticaria due to pseudoallergy — aspirin, nonselective nonsteroidal anti-inflammatory drugs, opiates, radiocontrast media; these cause urticaria without immune activation
Vaccination
Bee or wasp stings
Widespread reaction following localised contact urticaria — for example, latex
chronic uticaria causes ``
Chronic underlying infection, such as Helicobacter pylori (bowel parasites)
Chronic autoimmune diseases, such as systemic lupus erythematosus, thyroid disease, coeliac disease, vitiligo, and others.
Heat
Viral infection
Tight clothing
Drug pseudoallergy—aspirin, nonsteroidal anti-inflammatory drugs, opiates
Food pseudoallergy—salicylates, azo dye food colouring agents such as tartrazine (102), benzoate preservatives (210-220), and other food additives.
Inducible urticaria
Aquagenic urticaria
Hot or cold water
Fresh, salt, or chlorinated water
Vibratory urticaria
Jack hammer
Heat uricaria
Hot water bottle
Hot drink
Solar Uticaria
Sun exposure to non-habituated body sites
Often spare face, neck, hands
May involve long wavelength UV or visible light
Delayed pressure urticaria
Pressure on affected skin several hours earlier
Carrying heavy bag
Pressure from a seat belt
Standing on a ladder rung
Sitting on a horse
Contact urticaria
Eliciting substance absorbed through the skin or mucous membrane
Allergens (IgE-mediated): white flour, cosmetics, textiles, latex, saliva, meat, fish, vegetables
Pseudoallergens or irritants: stinging nettle, hairy caterpillar, medicines
Cholinergic urticaria
Sweat induced by exercise
Sweat induced by emotional upset
Hot shower
Cold urticaria
Cold air on exposed skin
Cold water
Ice block
Cryotherapy
Dermographism
Stroking or scratching the skin
Tight clothing
Towel drying after a hot shower
Managment of Utricaria
oral second-generation H1-antihistamine such as cetirizine or loratidine.
Onychomycosis
Fungal nail infection (onychomycosis) may involve any part of the nail, or the entire nail unit. Toenails are significantly more likely to become infected than fingernails
Severe Urticaria
A short course of an oral corticosteroid may required in addition to a non-sedating antihistamine
Toxic epidermal necrolysis
rare but important side effect of which to be aware of penicillins
life-threatening skin disorder that is most commonly seen secondary to a drug reaction
systemically unwell e.g. pyrexia, tachycardic
positive Nikolsky’s sign: the epidermis separates with mild lateral pressure
Drugs which induce TEN
phenytoin
sulphonamides
allopurinol
penicillins
carbamazepine
NSAIDs
Managment of TENs
stop precipitating factor
supportive care
often in an intensive care unit
volume loss and electrolyte derangement are potential complications
intravenous immunoglobulin has been shown to be effective and is now commonly used first-line
other treatment options include: immunosuppressive agents (ciclosporin and cyclophosphamide), plasmapheresis
Chlorphenamine- sedating or non-sedating?
sedating
Loratadine- sedating or non-sedating?
non-sedating
ceterazine- sedating or non-sedating
non-sedating
What is this?
Erythema multiforme
What is this?
Erythema multiforme
What is this?
Erythema multiforme
What is this?
Erythema nodosum
What is this?
Erythema nodosum
What is this?
Erythema nodosum
what is this?
Guttate psoriasis
What is this?
Guttate psoriasis
What is this?
Pityriasis rosea
Acanthosis nigricans
Symmetrical, brown, velvety plaques
can be found
* neck
* axilla
* groin
What is this?
Acanthosis nigricans
What is this?
Acanthosis nigricans
What is this?
Lichen Planus
What is this?
Lichen Planus- buccal mucosa
What is this?
Rosacea
What is this?
Rosacea
What is this?
Rosacea
What is this?
Seborrhoeic dermatitis
What is this?
Seborrhoeic dermatitis
What is this?
Fungal nail change
What is this?
Yellow nail syndrome **
What is this?
Blue nail- wilsons disease
What is this?
Nail pitting psoriasis
Mild nail psoriasis
What is this?
Actinic keratoses
What is this?
Impetigo
What is this?
venous leg ulcer
What is this?
Marjolin’s ulcer
What is this?
Marjolin’s ulcer
What is this?
Arterial ulcer
What is this?
Neuropathic ulcer
what is this?
Pyoderma gangernosum
Acne conglobate
*Extensive inflammatory papules, suppurative nodules (that may coalesce to form sinuses)
* cysts on the trunk
* most common in men
What is this?
BCC
What is this?
squamous cell carcinoma
What is this?
melanoma
class and features of cellulitis
